The present invention relates generally to new and novel improvements in printing ribbon cassettes and methods for assembly thereof. More particularly, the present invention relates to modifications for and methods of incorporating such modifications into printing ribbon cassette kits to fabricate printing ribbon cassettes having enhanced performance characteristics when used in conjunction with associated printing equipment.
One widely used cost effective method of printing printed images on printing media, such as paper, is impact printing. In impact printing, printed images are formed on the printing medium from the impact of a print head or print element against an inked printing ribbon, which in turn transfers the printed images onto the printing medium. In typical applications, the print head is selectively energized and moves laterally a predetermined distance towards the printing medium into contact with the inked printing ribbon. This forces preselected areas of the inked printing ribbon against the printing medium and backing platen. Some of the ink present in the inked printing ribbon is then transferred to the printing medium at the preselected areas of contact between the print head and the printing medium. The print head is then deenergized and moves laterally away from contact with the printing medium, resulting in a printed image which remains on the printing medium having a configuration corresponding to the preselected areas of contact between the print head, the inked printing ribbon, and the printing medium.
Two types of print heads are commonly used in conjunction with impact printing. A first type of print head contains an entire printed image in a single print element, as in the case of conventional typewriters. A second type of print head consists of a matrix of print wires which are selectively energized to form a variety of printed images on the printing medium, as in the case of so called "dot matrix" printers. This second type of print head consisting of a matrix of print wires generally results in a more compact configuration and is widely used as a cost effective method of printing printed images onto printing media.
Two types of inked printing ribbons are commonly used in conjunction with impact printing equipment. One type of inked printing ribbon has two discrete ends and the inked printing ribbon travels from a supply spool, across an interface between the print head and the printing medium, and then to a take-up spool. Once the length of such an inked printing ribbon has traveled across the interface between the print head and the printing medium and is wound on the take-up spool, it is generally necessary to insert a replacement filled supply spool and a replacement empty take-up spool. While it is sometimes possible to interchange the empty supply spool and the filled take-up spool and continue with the printing operation; doing so still requires an interruption of the printing operation and the operator must take time to change and rethread the inked printing ribbon. Also, some printers automatically switch the direction of travel of the inked printing ribbon when an end of the inked printing ribbon is reached. However, providing such a printing ribbon travel switching mechanism generally complicates the design of such printers, and adds to the cost and complexity of these types of printers.
Another commonly used inked printing ribbon is a continuous or endless loop inked printing ribbon which continues to pass across the interface between the print head and the printing medium until the ink supply in the inked printing ribbon is exhausted, or until the accumulation of wear and tear on the inked printing ribbon from the impact of the print elements damages the ink retaining substrate. Such continuous or endless loop inked printing ribbons are preferred in many applications because the darkness of the printed images being formed can be monitored by the operator and replacement of the inked printing ribbon can generally be performed at a time convenient to the operator.
To simplify the installation and removal of continuous or endless loop inked printing ribbons in printing equipment, continuous or endless loop inked printing ribbons are often enclosed in printing ribbon cassettes. Such printing ribbon cassettes commonly include a ribbon storage area, a printing ribbon drive mechanism which is generally driven by the printing equipment, an outlet pore, and an inlet port. A portion of the continuous or endless inked printing ribbon extends between the outlet port and the inlet port and passes through the interface between the print head and the printing medium. Continuous or endless loop printing ribbon cassettes can generally be quickly and easily inserted into the printing equipment and can also be quickly and easily removed and replaced when the quality of the printed images deteriorates to an undesirable level.
One piece of printing equipment currently being marketed is the IBM 4683 Model 3 printer manufactured by International Business Machines Corporation (IBM), located in Armonk, N.Y. Lexmark International, Inc. of Greenwich, Conn. markets a IBM 4683 printing ribbon cassette for use with this machine. This printing ribbon cassette is compatible with the IBM 4683 Model 3 printer, but is relatively expensive to purchase.
Turbon International (Turbon) of Wuppertal, West Germany markets a printing ribbon cassette kit, designated as IL 411.00, which, when assembled with a continuous or endless loop of inked printing ribbon, is compatible with the IBM 4683 Model 3 printer. Printing ribbon cassettes assembled utilizing the Turbon IL 411.00 printing ribbon cassette kit are desirable to customers since they can be generally purchased for much less than the Lexmark 4683 printing ribbon cassette being marketed by Lexmark.
However, printing ribbon cassettes assembled utilizing the Turbon IL 411.00 printing ribbon cassette kits have been found to result in an undesirable rate of performance failures when used in conjunction with IBM 4683 Model 3 printers. Such failures include the continuous or endless loop inked printing ribbon becoming wrapped around the drive gear mechanism, the continuous or endless loop inked printing ribbon coming out of the printing ribbon cassette nose clip member which positions the inked printing ribbon in the interface between the print head and the printing medium, and the continuous or endless loop inked printing ribbon coming out of the printing ribbon cassette altogether due to separation between the printing ribbon cassette base and the printing ribbon cassette cover. Such performance failures have resulted in the printing equipment experiencing an undesirable amount of down time, the scrapping of printing media due to defective or missing printed images, the scrapping of the defective printing ribbon cassettes, and possible damage to the printing equipment.
According, an object of the present invention is the provision of a modified continuous or endless loop printing ribbon cassette compatible with IBM 4683 Model 3 printers fabricated from a Turbon IL 411.00 printing ribbon cassette kit which provides enhanced performance characteristics when used in conjunction with IBM 4683 Model 3 printers and similar printing equipment.
Another object of the present invention is to provide a nose clip insert which can be utilized in conjunction with a Turbon IL 411.00 printing ribbon cassette kit to fabricate a continuous or endless loop printing ribbon cassette which is compatible with IBM 4683 Model 3 printers and which provides enhanced performance characteristics when used in conjunction with IBM 4683 Model 3 printers and similar printing equipment.
A further object of the present invention is the provision of a method of assembling a modified continuous or endless printing ribbon cassette using a Turbon IL 411.00 printing ribbon cassette kit to fabricate a continuous or endless loop printing ribbon cassette which is compatible with IBM 4683 Model 3 printers and which provides enhanced performance characteristics when used in conjunction with IBM 4683 Model 3 printers and similar printing equipment.
These and other objects of the present invention are attained by the provision of a continuous or endless loop printing ribbon cassette having a printing ribbon cassette body, a printing ribbon cassette nose clip member, and a continuous or endless loop inked printing ribbon. The printing ribbon cassette body includes a continuous or endless loop inked printing ribbon storage area, an outlet port, and an inlet port. The printing ribbon cassette nose clip member is positioned between the outlet port and the inlet port and locates the continuous or endless loop inked printing ribbon in proper orientation relative to the interface between the print head and the printing medium. A nose clip modification insert is provided which, when assembled to the printing ribbon cassette nose clip member, closes a preexisting opening in the printing ribbon cassette nose clip member and extends an outer surface of the printing ribbon cassette nose clip member an additional distance sufficient to protect or prevent the continuous or endless loop inked printing ribbon from being wrinkled or caught between the printing medium and the print head upon insertion of the printing medium into the printing equipment. In addition, a modified spring tensioner provides increased tension on the continuous or endless loop inked printing ribbon prior to its exit from the outlet port. Furthermore, the printing ribbon cassette base and the printing ribbon cassette cover are rigidly connected in the vicinity of the drive gear mechanism to prevent the escape of the continuous or endless loop inked printing ribbon from the printing ribbon cassette due to separation of the printing ribbon cassette base from the print ribbon cassette cover.
Other objects, advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.